Cu-6Ni-6Sn-xMn 합금의 시효거동에 미치는 Mn , Al , Ti , Si 의 영향

The effects of addition of Mn, Al, Ti and Si on the aging behavior in Cu-6Ni-6Sn-xMn (wt%) alloys were investigated by means of X-ray side band observation around (200)_α peak, hardness measurements and microstructural observations. The supersaturated solid solution α of Cu-6Ni-6Sn alloy decomposed via the spinodal mechanism to form the modulated structure on aging at temperatures below 350℃, then the matastable phase of γ` with DO_(22) structure formed later. However, when the alloy were aged at at temperatures above 450℃, the cellular structure consisting of αand γ phases formed. The decomposition process of Cu-6Ni-1.5Mn-6Sn alloy was similar to that of the Cu-6Ni-1.5Mn-6Sn alloy. In the alloys consisting more than 3 wt% Mn, however, neither the spinodal decomposition nor the formation of γ` were not occurred. The decomposition mode of the alloys were significantly altered by the small additions of Al, Ti or Si. Al, Ti and Si added alloys were hardened by the metastable CuAl₂, CuTi₂ and MnSi precipitates, respectively.